Aquihelicascus W. Dong, H. Zhang & Doilom, gen. nov.

Index Fungorum number: IF557806; Facesoffungi num- ber: FoF08721

Etymology: referring to the aquatic habitat and its similar- ity to Helicascus

Saprobic on submerged wood.

Sexual morph: Pseudos- tromata scattered, comprising brown to black fungal mate- rial growing in cortex of host cells, to uni- or multi-loculate, flattened at the basal region, horizontally arranged under the pseudostroma, carbonaceous or coriaceous, visible on the host surface as blackened ostiolar dots. Locules immersed, compressed subglobose to lenticular or sometimes triangu- lar, with ostiolate papilla. Ostiole central, rounded, peri- physate. Peridium comprising several layers of thin-walled angular cells, hyaline inwardly and dark at the outside, fus- ing with the host cells. Pseudoparaphyses numerous, cel- lular, hyaline, indistinctly septate, embedded in a gelatinous matrix. Asci 8-spored, bitunicate, clavate, long pedicellate, endoascus uncoiled, apically rounded, with an indistinct or distinct, trapezoidal ocular chamber. Ascospores mostly biseriate, sometimes overlapping uniseriate, straight or slightly curved, ellipsoidal to fusiform, with rounded ends, 1-septate, almost symmetrical, constricted at the septum, hyaline, smooth, thin-walled, lacking a mucilaginous sheath or appendage.

Asexual morph: Undetermined.

Type species: Aquihelicascus thalassioideus (K.D. Hyde& Aptroot) W. Dong & H. Zhang

Notes: – Aquihelicascus is introduced to accommodate one new comination A. thalassioideus and two new species A. songkhlaensis and A. yunnanensis. Aquihelicascus dif- fers from Helicascus in having clavate asci with uncoiled endoascus, and biseriate, ellipsoidal, symmetrical, hyaline ascospores with rounded ends. In contrast, Helicascus has subcylindrical asci with coiled endoascus, and uniseriate, obovoid, asymmetrical, brown ascospores with apiculate ends (Kohlmeyer 1969; Hyde 1991; Preedanon et al. 2017). All Aquihelicascus species were collected from freshwater habitats, whereas Helicascus species are from marine habi- tats. Aquihelicascus and Helicascus clustered separately in phylogenetic analyses (Zhang et al. 2013a; Luo et al. 2016b; Preedanon et al. 2017; this study, Fig. 84) which supports the placement of two different genera.

Aquihelicascus species have hyaline ascospores and are morphologically very similar. Among them, A. songkhlaen- sis possesses two-loculate pseudostromata and A. thalassioi- deus has the widest peridium. The phylogenetic analysis and single gene comparison can easily separate them.

Fig. 84 Phylogram generated from maximum likelihood analysis of combined LSU, SSU, ITS and TEF sequence data for species of Morospha- eriaceae. Bootstrap values for maximum likelihood equal to or greater than 75% and Bayesian posterior probabilities equal to or greater than 0.95 are placed near the branches as ML/BYPP. Newly generated sequences are in red and ex-type strains are in bold. The new species intro- duced in this study are indicated with underline. Freshwater strains are indicated with a red letter “F”. The tree is rooted to Latorua caligans CBS 576.65 (Latoruaceae)